The Solar Foundation’s National Solar Jobs Census methodology is aligned with the U.S. Department of Labor Bureau of Labor Statistics’ (BLS) methodology for its Quarterly Census of Employment and Wages and Current Employment Statistics (CES). Like the BLS, this study uses survey questionnaires and employer-reported data, though Solar Jobs Census surveys are administered by phone and email, as opposed to mail. This included approximately 59,300 phone calls and over 35,000 email invitations.

The National Solar Jobs Census 2017 includes data gathered between October and November 2017 from known and potential solar energy establishments or locations. The survey was administered by BW Research Partnership to a known universe of solar employers that included 9,488 separate establishments, and was derived from the Solar Energy Industry Association’s National Solar Database. Of these establishments, 2,389 provided information about their solar activities (or lack of solar activities), and 1,842 completed full or substantially completed surveys.

The survey was also administered to a stratified, clustered, random sampling of 168,305 establishments nationwide from various industries that are potentially solar-related. After an extensive cleaning and deduplication process, a sampling plan was developed that gathered information on the level of solar activity (including none) from 5,930 establishments. Of these, 207 establishments qualified for full surveys.

Since responses to the survey are often not representative by industry, a weighting adjustment (by size of segment) is applied to the primary value chain of the responding location. This prohibits inaccuracy of responses by value chain (over-representation or under-representation) and ensures an accurate read of employment and other responses within the survey. This level of sampling rigor provides a margin of error of +/-1.25% for the national jobs numbers.

Since 2010, The Solar Foundation has defined a solar job as one held by a worker spending at least 50% of his or her time on solar-related work. Census findings have consistently shown that roughly 90% of these workers (89% in 2017) spend 100% of their time on solar-related work.